1. Field of the Invention
The present invention relates to a straight or linear feed mechanism used for straight or linear motion feeding in various machines such as machine tools, general industrial machines, robots, and measuring instruments.
2. Description of the Prior Art
Convention straight or linear feed mechanisms have been suggested as disclosed in Japanese Utility Model Early-Disclosure No. 61-61362 and Japanese Patent Early-Disclosure No. 62-200016. These two devices are described below in reference to FIGS. 5 (a) and (b), respectively.
In the mechanism of Japan No. 61-61362, as shown in FIG. 5(a), a moving member c straddling a track member a is movably supported by straight or linear motion bearing mechanisms b, and a nut portion d of a ball screw is provided beside or atop the moving member c. A threaded shaft e is engaged with the nut portion d, and by turning the threaded shaft e, the nut portion d and the moving member c are moved along the track member a by the straight motion bearing mechanisms b.
In the mechanism of Japan 62-200016, as shown in FIG. 5(b), track members a and a' are provided on both sides of a moving member c along with a nut portion d of a ball screw. Straight or linear motion bearing mechanisms b and b' are provided between the moving member c and track members a and a' on both sides. By rotating the threaded shaft e engaged with nut portion d, the moving member c is moved along the track members a and a' disposed on both sides. Each of these two conventional straight feed mechanisms has problems which are solved by the present invention.
For example, as the conventional track member(s) a, the straight or linear motion bearing mechanisms b, and the threaded shaft e are installed separately at positions spaced apart from each other, such convention linear feed mechanisms have many problems. Such problems include: the number of parts required is large, many hours are required for fabrication, assembly is labor intensive, assembly accuracy such as achieving parallelism is relatively difficult to achieve, and the space occupied by the mechanism is relatively large.